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IndustryArena Forum > Machine Controllers Software and Solutions > Mach Software (ArtSoft software) > Odd repeatable stepper stalling - PULLING MY HAIR OUT!
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  1. #1
    Join Date
    Jan 2010
    Posts
    76

    Odd repeatable stepper stalling - PULLING MY HAIR OUT!

    Ok i've got a real head scratcher here. i built my machine about 6 years ago and it has mostly been a fun toy and learning experience. it has its quarks and so anytime it did something strange like have a random motor stall, i woudl just slow the speed down and try again.

    Fast forward to this weekend - i went through and rebuilt the parts of the machine that i knew to be troublesome, including doing a lot of alignment work on they Y axis, which is much smoother and stiffer now. Given this improvement, i expected to have better performance out of my machine.

    i was working on cutting out a sign and while cutting the numbers, the machine stalled in the Y axis. Now in the past i have run about 40 IPM cutting and had very good reliability and repeatability. i was trying 50 IPM when the stall happened. i lowered the speed down to 40 IPM and it ran fine as usual. With the improvements i made to my Y axis, i can easily run 150 IPM rapids with no stalling, and have intermittantly run as fast as 225 IPM so i did not expect any issues at 50 IPM.

    High Level Details:
    -stall occured in the middle of the axis but if i change my start point it will stall at the exact same place in the g code every time regardles of physical position on the y axis
    -there is no binding, it is very smooth
    -the stall always occurs during a g01 command to move x and y by a small amount (around 0.005" give or take)
    -the stall occurs both while cutting material and running in the air, so i dont think its torque related
    -I tried increasing the speed in 10 IPM increments up to 100 IPM and the stall still occurs every time
    -it never occurs at 40 IPM
    -Nema 23 305oz unipolar with HobbyCNC board. its a 2'x3' cutting area. Y axis is the 2' axis.
    -my machine almost never loses steps. if it is going to have a problem, it has a full on stall.
    -i have had this happen before in the past where it seems to stall at a cartin line of code, but i always chalked it up to binding.

    Things i tried:
    -changing Mach 3 step and direction pulse width up to the max of 5 us
    -using Sherine 1/2 step mode
    -changing kernal frequency (tried all settings)
    (note: i don't have shielded wire running my motors, in case that makes a difference in things to try)

    I need some help as i am not sure what other settings to try. I know my machine is capable of running much faster than 50 IPM so i am not sure why it keeps stalling at this one line of code

  2. #2
    Join Date
    Mar 2003
    Posts
    35538

    Re: Odd repeatable stepper stalling - PULLING MY HAIR OUT!

    Have you tried changing your acceleration settings at all?

    It could be resonance. If it is, then changing the acceleration may help.

    Is there a Z move when it's stalling?
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  3. #3
    Join Date
    Jan 2010
    Posts
    76

    Re: Odd repeatable stepper stalling - PULLING MY HAIR OUT!

    yes i tried slowing acceleration down to half and it still did it. Sorry i forgot to mention that. there is a z move the line before that move but not during that move.

  4. #4
    Join Date
    Mar 2003
    Posts
    35538

    Re: Odd repeatable stepper stalling - PULLING MY HAIR OUT!

    Try removing the Z move from the previous line and see if it still stalls.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  5. #5
    Join Date
    Jan 2010
    Posts
    76

    Re: Odd repeatable stepper stalling - PULLING MY HAIR OUT!

    removed the z move and it still stalls. here is a photo of the code. it line 600 that it stalls onClick image for larger version. 

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  6. #6
    Join Date
    Mar 2003
    Posts
    35538

    Re: Odd repeatable stepper stalling - PULLING MY HAIR OUT!

    So, it moves one way, then reverses and goes back, and that's where it's stalling.
    Do you have backlash comp turned on?
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  7. #7
    Join Date
    Jan 2010
    Posts
    76

    Re: Odd repeatable stepper stalling - PULLING MY HAIR OUT!

    yes backlash comp is on but currently set to 0 for y axis. let me turn it off completely and see if that changes anything. thanks for your help!

  8. #8
    Join Date
    Jan 2010
    Posts
    76

    Re: Odd repeatable stepper stalling - PULLING MY HAIR OUT!

    that fixed it! i ran it all the way up to 120 IPM with no hiccups whatsoever. I am still puzzled why Mach 3 would be sending any step to the motor considering i have the backlash on that axis set to a value of zero. it is only on my X and Z that i need the backlash comp (mostly the X, i haven't reworked that axis yet). Is it problematic to have a 0 setting with backlash comp on? should i set it for a value, like 0.001?

    I have the backlash speed set at 50%. It doesn't seem like that should be too fast.

    Thanks again for all your help.

  9. #9
    Join Date
    Mar 2003
    Posts
    35538

    Re: Odd repeatable stepper stalling - PULLING MY HAIR OUT!

    Never used backlash comp, but there are some YouTube videos that explain exactly how it works.

    I believe that the Shuttle Accel setting on the General Config screen also plays a role.

    It's always better to fix the mechanical issues if possible.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

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